Objective: To investigate the reliability of 3 scales used for assessment of pain in dogs. Design: Prospective study. Animals: 50 dogs that had surgery. Procedure: Dogs were allocated into 3 groups (group 1, 25 dogs assessed 1 hour after the end of surgery; group 2, 41 dogs assessed between 21 and 27 hours after the end of surgery; group 3, 16 dogs assessed on the day of surgery and on the subsequent day). Each dog was scored for pain 4 times by 3 (groups 1 and 3) or 4 (group 2) veterinarians, using all 3 scales (ie, simple descriptive, numerical rating, and visual analogue) during each scoring period. Analysis of data was performed using ANOVA, loglinear modeling, calculation of reproducibility coefficients, and Cohen's kappa statistic. Results: Significant variability existed among observers for use of all 3 scales. Variability among observers and between observers and dogs accounted for 29 to 36% of the total variability (group 1, 36.1 and 32.3% and group 2, 35.1 and 29.7%, for visual analogue scale and numerical rating scale scores, respectively). Kappa statistic values calculated for data obtained by use of the simple descriptive scale indicated that agreement was fair for the observers (group 1, 0.244 to 0.299; group 2, 0.211 to 0.368; group 3, 0.233 to 0.321). Clinical Implications: Analysis of pain score data in dogs must incorporate observer variability when more than 1 observer is used. Comparative analysis of data accrued from pain studies in various hospitals must account for this variability. (J Am Vet Med Assoc 1998;212:61–66)

Four groups of 20 dogs were anaesthetised by means of target‐controlled infusions of propofol designed to achieve 2·5 µg/ml, 3·0 µg/ml, 3·5 µg/ml or 4·0 µg/ml of propofol in blood. The dogs’ pulse rate and respiratory rate were recorded before premedication and induction, immediately after endotracheal intubation and three and five minutes later (times 0, 3 and 5, respectively), and their arterial blood pressure was recorded oscillometrically just before induction and at times 0, 3 and 5. The targets of 2·5, 3·0, 3·5 and 4·0 µg/ml resulted in the successful induction of anaesthesia in 13 (65 per cent), 16 (80 per cent), 20 (100 per cent) and 20 (100 per cent) of the dogs, respectively. The incidence of postinduction apnoea was 0 (0 per cent), one (5 per cent), two (10 per cent) and eight (40 per cent) at time 5 for groups 2·5, 3·0, 3·5 and 4·0 µg/ml, respectively, and its incidence at time 5 was significantly higher in the 4·0 µg/ml group (P<0·05) than in the other groups. In all the groups there was a significant (P<0·05) decrease in blood pressure between just before induction and the later measurements. Although there were no statistically significant differences between the groups in terms of inducing anaesthesia at a specific target, a target of 3·5 µg/ml appears to ensure a successful induction of anaesthesia without a significant increase in the incidence of apnoea.